Underwater dissolutional pitting on dolostones, Lake Huron-Georgian Bay, Ontario

This paper examines underwater dissolutional pitting along the dolomitic sh orelines of the Bruce Peninsula around Tobermory, Ontario. Research was con ducted from the modern spray and swash zone to depths of 25 m at four sites : Little Cove, Big Tub, Marr Lake, and Cove Island. The morphology of sampl e pits was measured, rock samples were collected, and comprehensive water a nalyses were completed. The most striking result to emerge from this work w as a strong positive relationship (r(2) = .93) between pit depth and water depth. Variations in the physical lithology obscured all other relationship s between the morphological parameters that were studied. The detailed vari ations of lithology between sites and between water depths at a given site are difficult to quantify and were not attempted in this project. The Tober mory sites are distinct because they have been both totally emerged and tot ally submerged during the last 12,000 years. A model to explain pit genesis including initiation and enlargement incorporating this post glacial lake level history is proposed.